LEASES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
ROU assets included within other long-term assets	$ 437	$ 410
Operating lease liabilities included within trade accounts payable and accrued expenses	129	116
Operating lease liabilities included within other long-term liabilities	355	332
Fixed operating lease costs	141	154
Variable lease costs	92	82
Sublease rental income	$ 36	$ 45
Weighted average remaining lease term (in years)	5 years 2 months 12 days	4 years 10 months 24 days
Weighted average discount rate (percent)	3.70%	4.10%
Operating lease cash payments	$ 146	$ 151
ROU asset, balance sheet line item	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Operating lease liabilities current, balance sheet line item	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent
Operating lease liabilities noncurrent, balance sheet line item	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent